Tuberculosis in Wildlife, Livestock and People in Nepal

Nepal is a small, landlocked country situated between India and Tibet, with a human population of approximately 27 million. Nepal is typical of many developing countries struggling to control tuberculosis (TB) in its population. Up to 45 percent of Nepal’s population is infected with TB with 44,000 active cases reported every year (Government of Nepal Ministry of Health and Population). Tuberculosis is also endemic in Nepal’s livestock, as it is in other countries in South Asia. Livestock tuberculosis is typically caused by Mycobacterium bovis, a slightly different organism than M. tuberculosis, which is more common in people. However, people are also susceptible to M. bovis infection and can contract this disease from contact with infected animals, eating contaminated poorly cooked meat and drinking unpasteurized milk. This disease is notoriously difficult to diagnose and track, as well as treat effectively. It often occurs with other chronic diseases, and more and more frequently involves dangerous drug resistant strains. Routine screening for tuberculosis in people does not differentiate M. bovis from M. tuberculosis infection. Consequently, a true understanding of the dynamics of tuberculosis in people and animals is often poorly understood. This picture is repeated around the world in many developing countries where M. bovis is endemic and is gaining interest in the human tuberculosis research community.

Tuberculosis also occurs in elephants and is well documented in captive settings in the United States and Europe. Interestingly, cases of elephant tuberculosis are most often diagnosed as M. tuberculosis, the organism responsible for human TB. This is unusual in animals and is most likely due to the intimate relationship between elephants and humans in captive settings. In Nepal, elephants are trained and kept for use in wildlife and forest management, tourism and for captive breeding in support of these activities. A recent study revealed that both M. bovis and M. tuberculosis likely occur in captive elephants in Nepal. This is not surprising due to the high prevalence of M. bovis in livestock that share pastures with these elephants, but it raises new questions that complicate an already complex picture.

In a conservation medicine project entitled “Tuberculosis in wildlife, livestock and humans across a shared landscape,” Tufts Center for Conservation Medicine faculty and students are beginning to explore the dynamics of these two organisms, M. bovisand M. tuberculosis, in the Terai ecosystem of southern Nepal. Ongoing studies are first focusing on development of diagnostic tests that will better differentiate these two organisms in cattle, buffalo, elephants and other wildlife, and eventually people. Future studies will attempt to track the transmission of these organisms and lead to policy recommendations for minimizing spread between wildlife, livestock and people in this region. Our partners, led by Elephant Care International, are focusing on managing this disease in captive elephants with a goal of effectively treating current cases and preventing future development of new cases or spread of this deadly disease to Nepal’s precious wild population of endangered Asian elephants.

Tuberculosis is a serious debilitating and often fatal disease of both humans and animals and a better understanding of the transmission of tuberculosis between animals and people will contribute to improved health and welfare for all concerned. Nepal’s situation is very typical of most Asian countries where elephants are found. The programs developed in Nepal will serve as a model for these countries and lead to greater understanding and more effective management of this disease across the region.

Nepal Study

In 2006, a large study was conducted in Nepal to screen a captive herd of elephants for tuberculosis. This project grew out of preliminary work by Cummings School of Veterinary Medicine student Karin Hamilton V06 and discussions with the chief wildlife veterinarian in Nepal, Dr. Kamal Gairhe. The project was developed by Hamilton, Dr. Gairhe, and an IAAS graduate student, Dr. Kamal Giri, and resulted in a large collaborative study led by Dr. Susan Mikota of Elephant Care International, involving many research scientists, elephant experts, and the Nepal government. More information about this work can be found on the Elephant Care International website.